In general, in a device that measures an unknown parameter of a received signal by using a plurality of sensors, it is necessary that a reception channel characteristic of each sensor is measured in advance, or that the reception characteristics of all the sensors are so calibrated as to be identical with each other. For that reason, it is necessary that observation data corresponding to the unknown parameter is observed, and the reception channel characteristic of each sensor is measured or calibrated.
As a related art to the unknown parameter estimation device, there is a multiple signal classification (MUSIC) method (for example, refer to Non-patent Document 1). In the related art using the MUSIC method, when a plurality of signals to be observed is high in correlation, for example, processing disclosed in Non-patent Document 2 needs to be conducted in a prestage.
Under such circumstances, in order to apply the pre-processing disclosed in Non-patent Document 2, it is necessary to use an observation device in which all of the sensors are identical in reception channel characteristic with each other, or a calibration device for calibrating the reception channel characteristics of all the sensors to be identical with each other. Because the former observation device is difficult to realize, the latter calibration device is generally used.
Further, as a related art that realizes the calibration device, there are, for example, devices disclosed in Non-patent Document 3 and Non-patent Document 4. In those related arts, a calibration matrix is estimated, which expresses, as a matrix, a plurality of calibration parameters for making the reception characteristics of the plurality of sensors identical with each other.    Non-patent Document 1: R. O. Schmidt, “Multiple emitter location and signal parameter estimation,” IEEE Trans. Antennas and Propagation, vol. AP-34, no. 3, pp. 276-280, March 1986 Non-patent Document 2: T. Shan, M. Wax, T. Kailath, “On spatial smoothing for direction-of-arrival estimation of coherent signals,” IEEE Trans. Acoustics, Speech and Signal Processing, vol. 33, no. 4, pp. 806-811, August 1985    Non-patent Document 3: B. Friedlander, A. J. Weiss, “Direction finding in the presence of mutual coupling,” IEEE Trans. Antennas and Propagation, vol. 39, no. 3, pp. 273-284, March 1991 Non-patent Document 4: C. M. S. See, “Sensor array calibration in the presence of mutual coupling and unknown sensor gains and phases,” Electronics Letters, vol. 30, pp. 373-374, March 1994